How exactly might the plan to put Syria's chemical weapons out of Bashar al-Assad's hands work? In London, Europe correspondent Mary Gearin spoke to Hamish de Bretton-Gordon, a former commanding officer at the UK's Joint Chemical, Biological, Radiological and Nuclear Regiment about the plan.

TIM PALMER: So precisely how might a plan to take Syria's chemical weapons out of Bashar al-Assad's hands actually work?

In London, Europe correspondent Mary Gearin spoke to Hamish de Bretton-Gordon, a former commanding officer at the UK's Joint Chemical, Biological, Radiological and Nuclear Regiment about that plan.

MARY GEARIN: Under international control: what do you believe that means? How feasible can that be?

HAMISH DE BRETTON-GORDON: Well I think it's feasible. I'm assuming what they're meaning is somebody like the UN or an independent body is going to take control of the Syrian chemical weapons stockpile and render them safe, basically destroy them. I think that's what we're talking about.

It's technically possible; in the environment of Syria, tremendously difficult. And I think we're going to have to approach it with some clear thought and lateral thought to be able to achieve it. But it is achievable.

MARY GEARIN: What makes it difficult in Syria at the moment?

HAMISH DE BRETTON-GORDON: Well it's, you know, there is a war going on and a very fierce war and battle is ensuing. To actually do this task, you would need to have a ceasefire. It's going to take some, if the chemical are going to be destroyed in place, that could take months, even years. But even to move them somewhere safe is going to take some time. But it could not be done without a ceasefire, so that's a huge challenge.

And the other is, you know, we're not entirely sure where all these chemical weapons are. We're expecting Assad to give us that information because he'll have the detail and he claims he's keen to help and support this initiative.

MARY GEARIN: If you are reasonably confident that you've got them, say, and then you have them in one spot, what happens then? How are they disposed of and how do you stop it from contaminating the area from getting into the wrong hands?

HAMISH DE BRETTON-GORDON: Well first of all how do you destroy them? You either sort of burn, incinerate them, or you do something called demilling, which is incineration and allowing the chemicals to degrade, which takes some time. Or you dig a big hole and put them in there or you store them somewhere else. So sort of four ways. The ideal way is demilling but that takes time. Incineration is the other way.

As far as do you get them all, I mean that's absolutely the key thing. We assume Assad, if he's willing to support, will hand over what he's got. I think the concern is whether there's already been proliferation, potentially in small amounts, potentially to some of the opposition or other terrorist organisations around the world.

Now if that's happened, that will be more difficult, but one is assuming that the opposition are going to support this initiative in Syria as well as the regime. And one would hope that they are party to it too, so anything that they might have, and there's you know no evidence they do, would also be taken under control by the international community.

MARY GEARIN: How difficult is it for intelligence communities to figure out if they've got them all?

HAMISH DE BRETTON-GORDON: Well, hugely difficult because we don't really know how many there are in the first place, which is why it's important that Assad gives us the detail, because his regime will have recorded everything they have and everything that they've made. Now unless they've destroyed that in the last couple of days, which would seem unlikely, that is the only way.

However, you know, the international intelligence community has been looking at this for some time and I'm sure the US, the UK, France and Russia have a good idea what they think is there, so that's why it needs to be a team effort by the G5, the UN, the Security Council, et cetera, to pull this off.

It's possible, but it's not going to be easy and I don't think anybody thinks it is.